00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

00 0 1 2 3 4 5 6 7 8 9 . SET EXP CHANGE SIGN E13 Clear Clear Display

01 TOTAL 00 TOTAL 01 TOTAL 02 TOTAL 03 TOTAL 04 TOTAL 05 TOTAL 06 TOTAL 07 TOTAL 08 TOTAL 09 TOTAL 10 TOTAL 11 TOTAL 12 TOTAL 13 TOTAL 14 TOTAL 15

02 + 00 + 01 + 02 + 03 + 04 + 05 + 06 + 07 + 08 + 09 + 10 + 11 + 12 + 13 + 14 + 15

03 - 00 - 01 - 02 - 03 - 04 - 05 - 06 - 07 - 08 - 09 - 10 - 11 - 12 - 13 - 14 - 15

04 × 00 × 01 × 02 × 03 × 04 × 05 × 06 × 07 × 08 × 09 × 10 × 11 × 12 × 13 × 14 × 15

05 ÷ 00 ÷ 01 ÷ 02 ÷ 03 ÷ 04 ÷ 05 ÷ 06 ÷ 07 ÷ 08 ÷ 09 ÷ 10 ÷ 11 ÷ 12 ÷ 13 ÷ 14 ÷ 15

06 STORE 00 STORE 01 STORE 02 STORE 03 STORE 04 STORE 05 STORE 06 STORE 07 STORE 08 STORE 09 STORE 10 STORE 11 STORE 12 STORE 13 STORE 14 STORE 15

07 RECALL 00 RECALL 01 RECALL 02 RECALL 03 RECALL 04 RECALL 05 RECALL 06 RECALL 07 RECALL 08 RECALL 09 RECALL 10 RECALL 11 RECALL 12 RECALL 13 RECALL 14 RECALL 15

08 SEARCH * RECALL * PRINT (*) GO J^IF0 J^IF+ SIN COS TAN RAD-DEG LOG_eX e^x X² √X LOAD PROG 1/X

09 MARK * STORE * α * STOP J^IF≠0 J^IF ERROR SIN^-1 COS^-1 TAN^-1 DEG-RAD LOG₁₀X 10^x INT X |X| END PROG RETURN

10 Call
10 00 Call
10 01 Call
10 02 Call
10 03 Call
10 04 Call
10 05 Call
10 06 Call
10 07 Call
10 08 Call
10 09 Call
10 10 Call
10 11 Call
10 12 Call
10 13 Call
10 14 Call
10 15

11 Call
11 00 Call
11 01 Call
11 02 Call
11 03 Call
11 04 Call
11 05 Call
11 06 Call
11 07 Call
11 08 Call
11 09 Call
11 10 Call
11 11 Call
11 12 Call
11 13 Call
11 14 Call
11 15

12 Call ROM
12 00 Call ROM
12 01 Call ROM
12 02 Call ROM
12 03 Call ROM
12 04 Call ROM
12 05 Call ROM
12 06 Call ROM
12 07 Call ROM
12 08 Call ROM
12 09 Call ROM
12 10 Call ROM
12 11 Call ROM
12 12 Call ROM
12 13 Call ROM
12 14 Call ROM
12 15

13 Call ROM
13 00 Call ROM
13 01 Call ROM
13 02 Call ROM
13 03 Call ROM
13 04 Call ROM
13 05 Call ROM
13 06 Call ROM
13 07 Call ROM
13 08 Call ROM
13 09 Call ROM
13 10 Call ROM
13 11 Call ROM
13 12 Call ROM
13 13 Call ROM
13 14 Call ROM
13 15

14 EXCHG 00 EXCHG 01 EXCHG 02 EXCHG 03 EXCHG 04 EXCHG 05 EXCHG 06 EXCHG 07 EXCHG 08 EXCHG 09 EXCHG 10 EXCHG 11 EXCHG 12 EXCHG 13 EXCHG 14 EXCHG 15

15 RECALL * Print * I/O * SEARCH ROM * SEARCH ROM * SEARCH ROM * SEARCH ROM * Call * (MARK) * STORE * α * INDIR * Call ROM * GROUP 1 * GROUP 2 * SEARCH *

* Two-step command sequences, described below

	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
00	0	1	2	3	4	5	6	7	8	9	.	SET EXP	CHANGE SIGN	E13	Clear	Clear Display
01	TOTAL 00	TOTAL 01	TOTAL 02	TOTAL 03	TOTAL 04	TOTAL 05	TOTAL 06	TOTAL 07	TOTAL 08	TOTAL 09	TOTAL 10	TOTAL 11	TOTAL 12	TOTAL 13	TOTAL 14	TOTAL 15
02	+ 00	+ 01	+ 02	+ 03	+ 04	+ 05	+ 06	+ 07	+ 08	+ 09	+ 10	+ 11	+ 12	+ 13	+ 14	+ 15
03	- 00	- 01	- 02	- 03	- 04	- 05	- 06	- 07	- 08	- 09	- 10	- 11	- 12	- 13	- 14	- 15
04	× 00	× 01	× 02	× 03	× 04	× 05	× 06	× 07	× 08	× 09	× 10	× 11	× 12	× 13	× 14	× 15
05	÷ 00	÷ 01	÷ 02	÷ 03	÷ 04	÷ 05	÷ 06	÷ 07	÷ 08	÷ 09	÷ 10	÷ 11	÷ 12	÷ 13	÷ 14	÷ 15
06	STORE 00	STORE 01	STORE 02	STORE 03	STORE 04	STORE 05	STORE 06	STORE 07	STORE 08	STORE 09	STORE 10	STORE 11	STORE 12	STORE 13	STORE 14	STORE 15
07	RECALL 00	RECALL 01	RECALL 02	RECALL 03	RECALL 04	RECALL 05	RECALL 06	RECALL 07	RECALL 08	RECALL 09	RECALL 10	RECALL 11	RECALL 12	RECALL 13	RECALL 14	RECALL 15
08	SEARCH *	RECALL *	PRINT (*)	GO	J^IF0	J^IF+	SIN	COS	TAN	RAD-DEG	LOG_eX	e^x	X²	√X	LOAD PROG	1/X
09	MARK *	STORE *	α *	STOP	J^IF≠0	J^IF ERROR	SIN^-1	COS^-1	TAN^-1	DEG-RAD	LOG₁₀X	10^x	INT X	\|X\|	END PROG	RETURN
10	Call 10 00	Call 10 01	Call 10 02	Call 10 03	Call 10 04	Call 10 05	Call 10 06	Call 10 07	Call 10 08	Call 10 09	Call 10 10	Call 10 11	Call 10 12	Call 10 13	Call 10 14	Call 10 15
11	Call 11 00	Call 11 01	Call 11 02	Call 11 03	Call 11 04	Call 11 05	Call 11 06	Call 11 07	Call 11 08	Call 11 09	Call 11 10	Call 11 11	Call 11 12	Call 11 13	Call 11 14	Call 11 15
12	Call ROM 12 00	Call ROM 12 01	Call ROM 12 02	Call ROM 12 03	Call ROM 12 04	Call ROM 12 05	Call ROM 12 06	Call ROM 12 07	Call ROM 12 08	Call ROM 12 09	Call ROM 12 10	Call ROM 12 11	Call ROM 12 12	Call ROM 12 13	Call ROM 12 14	Call ROM 12 15
13	Call ROM 13 00	Call ROM 13 01	Call ROM 13 02	Call ROM 13 03	Call ROM 13 04	Call ROM 13 05	Call ROM 13 06	Call ROM 13 07	Call ROM 13 08	Call ROM 13 09	Call ROM 13 10	Call ROM 13 11	Call ROM 13 12	Call ROM 13 13	Call ROM 13 14	Call ROM 13 15
14	EXCHG 00	EXCHG 01	EXCHG 02	EXCHG 03	EXCHG 04	EXCHG 05	EXCHG 06	EXCHG 07	EXCHG 08	EXCHG 09	EXCHG 10	EXCHG 11	EXCHG 12	EXCHG 13	EXCHG 14	EXCHG 15
15	RECALL *	Print *	I/O *	SEARCH ROM *	SEARCH ROM *	SEARCH ROM *	SEARCH ROM *	Call *	(MARK) *	STORE *	α *	INDIR *	Call ROM *	GROUP 1 *	GROUP 2 *	SEARCH *

Program Label Codes

SEARCH, MARK, and Call prefixes

The second step is a "label", used to implement goto and call. Any code may be used, however END PROG should be avoided.
Note: while the 15 08 variant of MARK is executed identically to 09 00, it does not actually mark a label. It is, in affect, a two-step no-op.

SEARCH, MARK, and Call prefixes
The second step is a "label", used to implement goto and call. Any code may be used, however END PROG should be avoided. Note: while the 15 08 variant of MARK is executed identically to 09 00, it does not actually mark a label. It is, in affect, a two-step no-op.

Program Register Codes

STORE and RECALL prefixes

The second step is a register number, 00 00 through 15 15. Note, registers above 15 06 are system memory and should not be used. The register 09 14 is the code for the END PROG command, and using it as a direct-target register in a program will affect program listings, recording/loading from tape, and inserting/deleting program steps.

STORE and RECALL prefixes
The second step is a register number, 00 00 through 15 15. Note, registers above 15 06 are system memory and should not be used. The register 09 14 is the code for the END PROG command, and using it as a direct-target register in a program will affect program listings, recording/loading from tape, and inserting/deleting program steps.

Indirect Codes

INDIR prefix

The second step is a register command. The operation is performed on the register number that is stored in that register. If register 05 contains 158.00000000, then INDIR +05 will add the display to register 158 (which is also known as 09 14). Note, this method of accessing register 09 14 (END PROG) will not interfere with program control functions.

A special case is for codes 00 rr where 'rr' specifies a register to be used indirectly. The integer, absolute value, contents of register 'rr' is added to the Program Counter (current program step). This effectively is a variable-length jump. The value is limited to 000 through 999.

INDIR prefix
The second step is a register command. The operation is performed on the register number that is stored in that register. If register 05 contains 158.00000000, then INDIR +05 will add the display to register 158 (which is also known as 09 14). Note, this method of accessing register 09 14 (END PROG) will not interfere with program control functions.
A special case is for codes 00 rr where 'rr' specifies a register to be used indirectly. The integer, absolute value, contents of register 'rr' is added to the Program Counter (current program step). This effectively is a variable-length jump. The value is limited to 000 through 999.

Alpha Codes

α prefix

00 00 through 03 15 Print character(s) to OutputWriter. Output stops when 02 02 is seen (not printed). Each character is prefixed by the "print mode" control character 02 08. Resulting symbols are described in table below.
NOTE: this is not a two-step command, but variable length. Code 02 02 terminates command.

04 00 through 07 15 Plot 00 00 through 03 15 on OutputWriter. The characters are prefixed by the "plotting mode" control character, 03 08, and each character by the "step control characters" needed to move the carriage based on registers 00 00 and 00 01. The integer portion of 00 00 controls movement in the Y direction, the integer portion of 00 01 controls movement in the X direction.
NOTE: this is not a two-step command, but variable length. Code 02 02 terminates command.

PRINT Turn on keyboard trace (Printer must be ON)

α Turn off keyboard trace

LOG_eX Turn on program trace (Printer must be ON)

e^X Turn off program trace

STOP 0.5 second pause

10 00 Value of π to display

10 xx Multiply display by 10^xx

11 xx Multiply display by 10^-xx

J^IF0 Jump if 00 00 = display

J^IF+ Jump if 00 00 >= display

SIN Jump if 00 00 < display

LOAD PROG Skip N records and load program from tape. N is integer portion of current display value.
STORE Record N+1 registers to tape. N is integer portion of current display value. Registers are recorded in reverse order, N through 00 00.
RECALL Load N+1 registers from tape. N is integer portion of current display value. Registers are loaded in reverse order, N through 00 00.

α prefix
00 00 through 03 15	Print character(s) to OutputWriter. Output stops when 02 02 is seen (not printed). Each character is prefixed by the "print mode" control character 02 08. Resulting symbols are described in table below. NOTE: this is not a two-step command, but variable length. Code 02 02 terminates command.
04 00 through 07 15	Plot 00 00 through 03 15 on OutputWriter. The characters are prefixed by the "plotting mode" control character, 03 08, and each character by the "step control characters" needed to move the carriage based on registers 00 00 and 00 01. The integer portion of 00 00 controls movement in the Y direction, the integer portion of 00 01 controls movement in the X direction. NOTE: this is not a two-step command, but variable length. Code 02 02 terminates command.
PRINT	Turn on keyboard trace (Printer must be ON)
α	Turn off keyboard trace
LOG_eX	Turn on program trace (Printer must be ON)
e^X	Turn off program trace
STOP	0.5 second pause
10 00	Value of π to display
10 xx	Multiply display by 10^xx
11 xx	Multiply display by 10^-xx
J^IF0	Jump if 00 00 = display
J^IF+	Jump if 00 00 >= display
SIN	Jump if 00 00 < display
LOAD PROG	Skip N records and load program from tape. N is integer portion of current display value.
STORE	Record N+1 registers to tape. N is integer portion of current display value. Registers are recorded in reverse order, N through 00 00.
RECALL	Load N+1 registers from tape. N is integer portion of current display value. Registers are loaded in reverse order, N through 00 00.

Print Codes

Print prefix, and PRINT inside a program

xx 00 through xx 10 Print with 0-10 decimal places

xx 11 through xx 14 print in scientific notation

-- 15 prints blank line

'xx' prints letter "tag" in column 21

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

X Y Z A B C D E F G H I J K L M

Block I/O Codes

I/O prefix

00 00 through 09 15 Print display, formatted, to OutputWriter (device 1). First number is number of (blank-filled) integer places, second is number of decimal places. 00 xx is for scientific notation, also xx 11 through xx 15.

10 xx Jump if 00 00 = display (string compare, not numeric)

11 xx Jump if 00 00 ≠ display (string compare, not numeric)

12 xx Print field of xx blanks to OutputWriter.

13 00 through 13 07 page-in blocks of program steps from "device 2". "Source" address is in 00 00 (integer portion, 0 - 16M). In 00 01 is the starting program step number (integer portion, 0000 - 1847). Length determined by 'xx':

00 01 02 03 04 05 06 07

1 step 8 steps 16 steps 32 steps 64 steps 128 steps 256 steps 64 steps

13 08 through 13 15 page-out blocks of program steps to "device 2". "Destination" address is in 00 00 (integer portion, 0 - 16M). In 00 01 is the starting program step number (integer portion, 0000 - 1847). Length determined 'xx':

08 09 10 11 12 13 14 15

1 step 8 steps 16 steps 32 steps 64 steps 128 steps 256 steps 64 steps

14 xx same as 10 xx.

15 xx same as 11 xx.

Group I/O Codes

GROUP 1 or GROUP 2 prefix

Send next code to device(s) on CN-36 port. In program, issues IOB=0, then IOB=4 (GROUP 1) or IOB=5 (GROUP 2) with data, then program stops (requires GO or PRIME to continue). Wang keyboard is locked, so GO must be generated by device. Device (and/or User) generates input codes, which are either interpreted by the running calculator (Run Mode) or placed in program memory (Learn Mode). The input stream is terminated by a GO command. Somce devices have special methods of generating the GO command, for example the TTY allows the user to type Ctrl-A to cause a GO, or the Micro-Interface generates a GO when data hase been acquired and transferred to the calculator.

Known Device Codes

GROUP 1
04 08 Run Mode Model 614 Mark-Sense Card Reader

GROUP 2
04 08 Learn Mode

GROUP 2
04 12 Run Mode Model 611 Input/Output Writer

GROUP 2
04 13 Learn Mode

GROUP 2
04 11 Learn Mode Model 622 Keyboard

GROUP 1
00 00 Run Mode Model 603 Paper-Tape Reader

GROUP 1
00 07 Skip to
Carriage-return

GROUP 1
07 xx Run Mode Model 605 Micro-Interface ('xx' configurable)

GROUP 1
15 00 Start Paper-Tape
Run Mode Model 607 TTY-Interface

GROUP 1
15 01 - 15 04 Print "1" (.."4")
Run Mode

GROUP 1
15 05 - 15 15 Run Mode

GROUP 2
15 00 Start Paper-Tape
Learn Mode

GROUP 2
15 01 - 15 04 Print "1" (.."4")
Learn Mode

GROUP 2
15 05 - 15 15 Learn Mode

GROUP 1 or GROUP 2 prefix
Send next code to device(s) on CN-36 port. In program, issues IOB=0, then IOB=4 (GROUP 1) or IOB=5 (GROUP 2) with data, then program stops (requires GO or PRIME to continue). Wang keyboard is locked, so GO must be generated by device. Device (and/or User) generates input codes, which are either interpreted by the running calculator (Run Mode) or placed in program memory (Learn Mode). The input stream is terminated by a GO command. Somce devices have special methods of generating the GO command, for example the TTY allows the user to type Ctrl-A to cause a GO, or the Micro-Interface generates a GO when data hase been acquired and transferred to the calculator.
Known Device Codes
GROUP 1 04 08	Run Mode	Model 614 Mark-Sense Card Reader
GROUP 2 04 08	Learn Mode
GROUP 2 04 12	Run Mode	Model 611 Input/Output Writer
GROUP 2 04 13	Learn Mode
GROUP 2 04 11	Learn Mode	Model 622 Keyboard
GROUP 1 00 00	Run Mode	Model 603 Paper-Tape Reader
GROUP 1 00 07	Skip to Carriage-return
GROUP 1 07 xx	Run Mode	Model 605 Micro-Interface ('xx' configurable)
GROUP 1 15 00	Start Paper-Tape Run Mode	Model 607 TTY-Interface
GROUP 1 15 01 - 15 04	Print "1" (.."4") Run Mode
GROUP 1 15 05 - 15 15	Run Mode
GROUP 2 15 00	Start Paper-Tape Learn Mode
GROUP 2 15 01 - 15 04	Print "1" (.."4") Learn Mode
GROUP 2 15 05 - 15 15	Learn Mode

Character Codes

OutputWriter (IBM Selectric) Character Codes

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

00 - y space back space q p = j tab / set tab clr tab , ; f g

01 w s shift dn shift up i ' . ½ return index o index rev index a r v m

02 b h step x+ step x- k e n t print mode l step y+ step y- c d u x

03 9 0 step x+y+ step x-y+ 6 5 2 z plot mode 4 step x+y- step x-y- 8 7 3 1

S
H
I
F
T
E
D _ Y space back space Q P + J tab ? set tab clr tab , : F G

W S shift dn shift up I " . ¼ return index O index rev index A R V M

B H step x+ step x- K E N T print mode L step y+ step y- C D U X

( ) step x+y+ step x-y+ ¢ % @ Z plot mode $ step x+y- step x-y- * & # !

OutputWriter (IBM Selectric) Character Codes
	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
00	-	y	space	back space	q	p	=	j	tab	/	set tab	clr tab	,	;	f	g
01	w	s	shift dn	shift up	i	'	.	½	return index	o	index	rev index	a	r	v	m
02	b	h	step x+	step x-	k	e	n	t	print mode	l	step y+	step y-	c	d	u	x
03	9	0	step x+y+	step x-y+	6	5	2	z	plot mode	4	step x+y-	step x-y-	8	7	3	1
S H I F T E D	_	Y	space	back space	Q	P	+	J	tab	?	set tab	clr tab	,	:	F	G
W	S	shift dn	shift up	I	"	.	¼	return index	O	index	rev index	A	R	V	M
B	H	step x+	step x-	K	E	N	T	print mode	L	step y+	step y-	C	D	U	X
(	)	step x+y+	step x-y+	¢	%	@	Z	plot mode	$	step x+y-	step x-y-	*	&	#	!

Flatbed Plotter Character Codes

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

00 - Y space / Q P + J } ? = { , : F G

01 W S pen dn pen up I ' . n/a return index? O index? rev index? A R V M

02 B H step x+ step x- K E N T print mode 1 step y+ step y- C D U X

03 9 0 step x+y+ step x-y+ 6 5 2 Z plot mode 4 step x+y- step x-y- 8 7 3 L

04 - Y space / Q P + J } ? = { , : F G

05 W S plot move I ' . n/a chr size O chr space home A R V M

06 B H step x+ step x- K E N T print mode 1 step y+ step y- C D U X

07 9 0 step x+y+ step x-y+ 6 5 2 Z plot mode 4 step x+y- step x-y- 8 7 3 L

Flatbed Plotter Character Codes
	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
00	-	Y	space	/	Q	P	+	J	}	?	=	{	,	:	F	G
01	W	S	pen dn	pen up	I	'	.	n/a	return index?	O	index?	rev index?	A	R	V	M
02	B	H	step x+	step x-	K	E	N	T	print mode	1	step y+	step y-	C	D	U	X
03	9	0	step x+y+	step x-y+	6	5	2	Z	plot mode	4	step x+y-	step x-y-	8	7	3	L
04	-	Y	space	/	Q	P	+	J	}	?	=	{	,	:	F	G
05	W	S	plot	move	I	'	.	n/a	chr size	O	chr space	home	A	R	V	M
06	B	H	step x+	step x-	K	E	N	T	print mode	1	step y+	step y-	C	D	U	X
07	9	0	step x+y+	step x-y+	6	5	2	Z	plot mode	4	step x+y-	step x-y-	8	7	3	L

Teletype Character Codes

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

00 - Y space n/a Q P = J n/a / DC2 DC4 , ; F G

01 W S shift dn shift up I ' . ! CR/LF O LF n/a A R V M

02 B H n/a n/a K E N T n/a 1 n/a n/a C D U X

03 9 0 n/a n/a 6 5 2 Z n/a 4 n/a n/a 8 7 3 L

S
H
I
F
T
E
D n/a Y space n/a Q P + J n/a ? DC2 DC4 , : F G

W S shift dn shift up I " . n/a CR/LF O LF n/a A R V M

B H n/a n/a K E N T n/a 1 n/a n/a C D U X

( ) n/a n/a n/a % @ Z n/a $ n/a n/a * & # L

Teletype Character Codes
	00	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15
00	-	Y	space	n/a	Q	P	=	J	n/a	/	DC2	DC4	,	;	F	G
01	W	S	shift dn	shift up	I	'	.	!	CR/LF	O	LF	n/a	A	R	V	M
02	B	H	n/a	n/a	K	E	N	T	n/a	1	n/a	n/a	C	D	U	X
03	9	0	n/a	n/a	6	5	2	Z	n/a	4	n/a	n/a	8	7	3	L
S H I F T E D	n/a	Y	space	n/a	Q	P	+	J	n/a	?	DC2	DC4	,	:	F	G
W	S	shift dn	shift up	I	"	.	n/a	CR/LF	O	LF	n/a	A	R	V	M
B	H	n/a	n/a	K	E	N	T	n/a	1	n/a	n/a	C	D	U	X
(	)	n/a	n/a	n/a	%	@	Z	n/a	$	n/a	n/a	*	&	#	L

The codes highlighted red are generated by the calculator and have unknown results if embedded in an ALPHA command. The calculator indicates the X and Y delta (registers 01 and 00, respectively) by issuing an appropriate number of the step codes, and the output device effectively counts them and performs the plotting motion.

The codes highlighted green are deviations from the OutputWriter, but only affect the ways strings are created by the programmer. The calculator microcode does not generate these. Note, however, that the IBM Selectic "Shift Up" and "Shift Down" codes have conflicting meanings with the Flatbed Plotter. Software written for the OutputWriter will probably not work without modification on the Flatbed Plotter. However, the modifications are probably limited to the ALPHA - ALPHA END sequences. Note, some commands require X and Y delta values that are used as parameters, not carriage movement.

The codes highlighted blue are plotted characters, the X and Y delta values are used to move the pen to the desired position where the indicated character is drawn. Note, only the first character of a string should be marked as plotted, or else each character will be speparated from the last by the X and Y delta.

The codes highlighted gray indicate deviation from the normal shifted mode of the character but are otherwise still aligned with the Selectric codes.

The codes highlighted yellow are unknown/undefined.

Note, the interface to the device only supports 6 bits. The above tables indicate what a programmer would put in an ALPHA - ALPHA END sequence to produce the indicated results. The device interprets the codes 0x00 through 0x3f according to state previously set up (e.g. plot mode or print mode).

Note the reversal of "1" and "L" in the Plotter/Teletype tables. The IBM Selectric considered the digit 1 to be redundant with lower-case ell. Many typeballs replaced "1" with other special characters. Because of this, the Wang microcode could not assume that it could print a "1" using the code for "1". Therefor, it uses lower case ell. In order to use the same microcode for both the Output Writer and the Plotter, the plotter's character decoding had to interpret lower case ell as "1" and use the encoding normally assigned to "1" as "L". This means that programs written for the Output Writer may not be completely compatable with the Plotter/Teletype.

"DC2" and "DC4" are ASCII control characters that cause the Teletype paper tape punch to turn on and off, respectively.